On 11 August, the government of Russia approved the first Covid-19 vaccine worldwide, developed by the Gamaleya Research Institute in Moscow and the Russian Ministry of Defense. However, the available clinical trial data originated from a Phase I / II trial comprising 38 trial participants who were followed for two months. This will not be enough to convince the global community of the vaccine’s potential. Only large-scale trials with a longer duration can determine if the vaccine can provide a durable response against the SARS-CoV-2 virus while being safe—the latter being especially important as a Covid-19 vaccine will be given to hundreds of millions of people.
Still, the Gamaleya vaccine that will be called ‘Sputnik V’ internationally may be both effective and safe. It is based on adenovirus vectors Ad5 and Ad26, which deliver the sequence for the SARS-CoV-2 spike protein. This is a similar technology to CanSino and AstraZeneca / Oxford University’s vaccine candidates, which have shown good early clinical results. Being the first country to successfully develop a Covid-19 vaccine would be a big boost to Russia both economically and for the country’s morale, since Russia has seen the fourth-highest number of confirmed Covid-19 cases. Companies and regulatory agencies from the US and China have both noted that a longer study than the Phase I / II is necessary to demonstrate protection, and noted that standards for clinical trials are not as transparent in Russia as in other countries.
Sputnik V is planned to be offered in stages, with Phase III participants and Russian health workers treating Covid-19 patients getting first access. It is unclear when enough vaccine doses will be available in the country for the start of mass vaccination, making this approval announcement less impactful. International collaborations for the production of the vaccine are planned, but other countries will likely wait for additional protection and safety data before rolling out the vaccine. For example, China has developed multiple vaccines that have shown some form of efficacy against the virus, but none were approved, likely because regulators understood that the data for these vaccines were insufficient for determining overall effectiveness. However, China has begun using CanSino’s Covid-19 vaccine, but only in its military.
In addition to the lack of long-term durability data, the use of adenovirus vectors poses the risk of reduced vaccine efficacy due to high pre-existing immunity to the viral vector, as Phase II results of CanSino’s Covid-19 vaccine have shown. These vaccines will be very useful as first-generation vaccines to slow the spread of SARS-CoV-2 and Covid-19, but if no long-term immunity can be achieved with two doses of the adenovirus vector-based vaccine, it is unclear whether annual vaccinations using this technology will offer sufficient protection in the future.